It is well known to line the inner side of a furnace shell of a metallurgical furnace, in particular a blast furnace, with cooling plates. Such a cooling plate, also called “stave”, comprises a rectangular, solid plate body with cooling passages therein. Connection pieces, which protrude from the rear side of the cooling plate, debouch into the cooling passages of the cooling plate. These connection pieces are led in a sealed manner through connection openings in the furnace shell. At the outer side of the furnace shell, flexible metal tubes are used to interconnect the connection pieces of adjacent cooling plates and to connect the cooling plates to a cooling water distribution circuit.
The plate body of such a cooling plate is made either from cast iron (in particular modular cast iron) or from copper or a copper alloy, or more recently also from steel. In cooling plates made from cast iron, the cooling passages are generally formed by cast-in U-shaped steel tubes, wherein the ends of a cast-in tube protrude from the rear side of the plate body as connection pieces. In virtually all cooling plates made from copper or steel, however, the cooling passages are directly formed in the solid cooling plate body.
DE 2 907 511 discloses a cooling plate which is made from a forged or rolled block of copper. The cooling passages in the copper block are blind bores produced by mechanical deep-drilling. The openings of these blind bores are sealed off by soldering or welding plugs therein. Connecting bores are drilled from the rear side of the plate into the blind bores, and connection pieces for the coolant feed or coolant return are inserted into these connecting bores and soldered or welded in place.
WO 98/30345 describes a process for manufacturing a cooling plate in which a blank of the cooling plate is produced by continuous casting. Inserts in the continuous-casting mould produce passages running in the casting direction, which form the cooling passages in the finished cooling plate. A plate is separated from the continuously-cast blank by making two cuts transversely with respect to the casting direction, thus forming two end faces, wherein the distance between these two end-faces corresponds to the desired length of the cooling plate. In the next manufacturing step, connection bores are drilled into the plate body perpendicular to its rear surface, so as to open into the through-passages. Thereafter connection pieces are inserted into the connection bores and soldered or welded in place and the end-side openings of the passages are sealed off by soldering or welding plugs therein.
The processes described in DE A 2907511 and in WO 98/30345 both enable high-quality cooling plate bodies to be produced from copper or copper alloys. However, compared to cooling plates with cast-in cooling tubes or compared to mould-cast cooling plates, the finished cooling plates produced by both processes have the drawback of relatively high pressure losses in the transition regions between the connection pieces and the cooling passages.
WO 00/36154 proposes to reduce the pressure losses in copper cooling plates with cast or drilled cooling passages by inserting a shaped piece into a cut-out in the cooling plate body, so as to form a diverting passage with optimised flow conditions for the cooling medium. However, this solution is relatively labour-intensive and results therefore in higher production costs for the cooling plates.